In order to reduce power requirements, materials, and labor of a work vehicle having a plurality of fluid pumps serving a plurality of fluid circuits each having at least one work element, it is desirable to provide means for controllably passing fluid between the fluid circuits in response to power demands of said circuits.
This invention therefore resides in a fluid system of work elements of a work vehicle having a pilot pump and first and second fluid circuits. Each of the first and second fluid circuits has a pump connected to a respective work element through a control valve assembly for controlling the flow of fluid from the respective pump to the respective work element and a primary pilot control valve positioned between the pilot pump and the respective control valve assembly for altering a pilot pump signal, delivering a resultant signal, and controlling the operation of the respective control valve assembly in response to said resultant signal. A control means is provided for passing fluid between the first and second fluid circuits. The control means is responsive to said resultant signals from the first and second primary pilot control valves.
A signal means is provided for sensing the load pressure of each circuit and delivering respective first and second control signals to a signal control means. The signal control means controllably combines the first and second control signals as a pump control signal in response to the magnitude of the resultant signals of each circuit. Pump control means associated with each pump receives the pump conrol signal and provides control of said pump output in response thereto.